Thanks to everyone who helped me in my previous posts as now i am a proud owner of my very own silk backed spotted gum bow it is around 40-45pds at 29inches and seems to shoot quite well however the arrows arent flying straight out of the bow im hoping that feather fletching instead of the plastic will increase the stability out of the bow.
anyway ive built one now im addicted even more so.
So ive started another bow this one will be bamboo backed and i have a few more questions.
How thick should the bamboo backing be if my spotted gum board is 17mm at the handle and 12mm at the tips.
Also can i just use PVA glue to stick it on.
Thanks
bamboo backing
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Running Bear Eagle Eye
- Posts: 78
- Joined: Fri Jul 28, 2006 4:56 pm
- Location: Melbourne
Hi Daniel,
I have found that it is better to cut the bamboo back the same as the plan of the bow and then remove the softer inner until you have an almost knife edge on the bamboo. You will find that this will give you a taper on the bamboo. The thickness of your spotted gum from handle to tip is not too critical at this stage as excess will be removed during the tillering process. Don't underestimate the power of bamboo. You could try pva but I would suggest a two pack glue such as Techniglue as it will give a much better result.
Daryl.
PS Will email the flatbow worksheet when I can compress it enough.
I have found that it is better to cut the bamboo back the same as the plan of the bow and then remove the softer inner until you have an almost knife edge on the bamboo. You will find that this will give you a taper on the bamboo. The thickness of your spotted gum from handle to tip is not too critical at this stage as excess will be removed during the tillering process. Don't underestimate the power of bamboo. You could try pva but I would suggest a two pack glue such as Techniglue as it will give a much better result.
Daryl.
PS Will email the flatbow worksheet when I can compress it enough.
Hi Daniel,
Regarding the arrow flight from your new bow you did not mention how far past centre the arrow shelf or knuckle is. The further the arrow is past centre the more it has to flex around the handle once you loose the arrow. Once loosed the arrow is still in contact with the string until the string reaches brace height and then has to flex around the handle. I think it is a case where you will have to experiment with different spined arrows to see which gives the best results as well as taking into account the overall mass weight of the arrow for better cast. Usually I nock an arrow and check to see where it comes in contact with the handle and if needed remove wood from the belly side of the shelf to bring the arrow angle closer to centre. I am the first to admit that I am not an expert in arrow dynamics but basic principles do exist.
Regards, Daryl.
Regarding the arrow flight from your new bow you did not mention how far past centre the arrow shelf or knuckle is. The further the arrow is past centre the more it has to flex around the handle once you loose the arrow. Once loosed the arrow is still in contact with the string until the string reaches brace height and then has to flex around the handle. I think it is a case where you will have to experiment with different spined arrows to see which gives the best results as well as taking into account the overall mass weight of the arrow for better cast. Usually I nock an arrow and check to see where it comes in contact with the handle and if needed remove wood from the belly side of the shelf to bring the arrow angle closer to centre. I am the first to admit that I am not an expert in arrow dynamics but basic principles do exist.
Regards, Daryl.
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Running Bear Eagle Eye
- Posts: 78
- Joined: Fri Jul 28, 2006 4:56 pm
- Location: Melbourne
Daryl
The arrow rest is about 3cm above centre is that to much?
The arrows im using are my carbons i use for my 70pound compound bow
they are only about 430grain and have a spine of 300.
I plan on getting 700+grain preferebly wood if i can find the shafts but most likely i will get aluminium and im unsure of the spine.
At the moment my bamboo backing is about 4-5mm thick is this to thick and how much poundage would you estimate this would add.
Thanks
The arrow rest is about 3cm above centre is that to much?
The arrows im using are my carbons i use for my 70pound compound bow
they are only about 430grain and have a spine of 300.
I plan on getting 700+grain preferebly wood if i can find the shafts but most likely i will get aluminium and im unsure of the spine.
At the moment my bamboo backing is about 4-5mm thick is this to thick and how much poundage would you estimate this would add.
Thanks
Hi Daniel,
I think you misunderstood my message. I was meaning left to right not up or down. Forget shooting carbons, go to woods mayby around 450 to 500 on the spine jig. Make a few arrows around this reading shoot them and then go up or down depending on performance. The lower the reading on the spine scale the stiffer they are.
Daryl.
I think you misunderstood my message. I was meaning left to right not up or down. Forget shooting carbons, go to woods mayby around 450 to 500 on the spine jig. Make a few arrows around this reading shoot them and then go up or down depending on performance. The lower the reading on the spine scale the stiffer they are.
Daryl.
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Running Bear Eagle Eye
- Posts: 78
- Joined: Fri Jul 28, 2006 4:56 pm
- Location: Melbourne
Hi Daniel,
2 cm off centre will make arrow matching a lot more difficult. If you can reduce this without comprising the integrity of the bow this would be preferable. Also reduce the thickness on the belly side of the window so that the arrow makes contact to the side of the bow closer to the back. If your local archery supplier cannot supply suitable woods put your request on the site and I am sure someone will be able to pass on information on where you can get suitable woods. Most archery shops tend to ignore the self bow market so you have to look around.
The bamboo used for the back and or belly laminations are cut to the plan of limbs and the softer inner pith of bamboo is removed so that the edges are almost knife edge. The end result should be that the crown of the bamboo at the handle end of the lamination is 3 to 4 mm and at the tip about 1 mm. depending on limb width at the handle and tip and the diameter of the bamboo pole that the backing was cut from.
There may be some more helpful information in the items that I submitted in the ‘Asian composite build along’ and ‘A New Hunting Bow and Change Out Of $25-00.’
Daryl.
2 cm off centre will make arrow matching a lot more difficult. If you can reduce this without comprising the integrity of the bow this would be preferable. Also reduce the thickness on the belly side of the window so that the arrow makes contact to the side of the bow closer to the back. If your local archery supplier cannot supply suitable woods put your request on the site and I am sure someone will be able to pass on information on where you can get suitable woods. Most archery shops tend to ignore the self bow market so you have to look around.
The bamboo used for the back and or belly laminations are cut to the plan of limbs and the softer inner pith of bamboo is removed so that the edges are almost knife edge. The end result should be that the crown of the bamboo at the handle end of the lamination is 3 to 4 mm and at the tip about 1 mm. depending on limb width at the handle and tip and the diameter of the bamboo pole that the backing was cut from.
There may be some more helpful information in the items that I submitted in the ‘Asian composite build along’ and ‘A New Hunting Bow and Change Out Of $25-00.’
Daryl.
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Running Bear Eagle Eye
- Posts: 78
- Joined: Fri Jul 28, 2006 4:56 pm
- Location: Melbourne